The one-dimensional, spherical coordinate, non-linear partial differential equation of transient heat conduction through a hollow spherical thermal insulation material of a thermal conductivity temperature dependent property proposed by an available empirical function is solved analytically using Kirchhoff’s transformation. It is assumed that this insulating material is initially at a uniform temperature. Then, it is suddenly subjected at its inner radius with a step change in temperature. Four thermal insulation materials were selected. An identical analytical solution was achieved when comparing the results of temperature distribution with available analytical solution for the same four case studies that assume a constant thermal con

Background: The purpose of this study was to verify the influence of post- pressing time of acrylic resin (immediate, 6, 12 and 24 hour) on the dimensional accuracy of denture base whish is a critical factor in the retention and stability of the complete denture that may occur during polymerization shrinkage. Materials and Methods: Forty maxillary stone casts were poured in plastic mold (Columbia Dentoform corp. NEW YORK, type III dental stone (Geastone, Zeus Sri Loc.Tamburine Roccastrada, GR, Italy). The stone casts were randomly assigned into 4 groups of 10 specimens each according to the post-pressing times into (immediate, 6, 12 and 24 h.). Heat cure acrylic resin denture base was constructed according to the previously mentioned pressi

Background: Polymethyl methacrylate (PMMA) is used in denture fabrication and considered as the most reliable material for the construction of removable prosthodontic appliances. The material is far from ideal in fulfilling the mechanical requirements and the effect of autoclave processing has not been fully determined. The purpose of this study was to evaluate the effect of addition of salinized (ZrO2) Nano fillers in percentages 3%, 5% and 7% by weight on some properties of heat cured acrylic processed the by autoclave and compare it with 0% (control) group . Materials and methods: The silanized(ZrO2) Nano-particles was added to PMMA powder by weight in three different percentages 3%, 5% and 7%, mixed by probe ultra-sonication machine.

The one-dimensional, cylindrical coordinate, non-linear partial differential equation of transient heat conduction through a hollow cylindrical thermal insulation material of a thermal conductivity temperature dependent property proposed by an available empirical
function is solved analytically using Kirchhoff’s transformation. It is assumed that this insulating material is initially at a uniform temperature. Then, it is suddenly subjected at its inner radius with a step change in temperature. Four thermal insulation materials were selected. An identical analytical solution was achieved when comparing the results of temperature distribution with available analytical solution for the same four case studies that assume a constant the

This paper aims to study the effect of circular Y-shaped fin arrangement to improve the low thermal response rates of a double-tube heat exchanger containing Paraffin phase change material (PCM). ANSYS software is employed to perform the computational fluid dynamic (CFD) simulations of the heat exchanger, including fluid flow, heat transfer, and the phase change process. The optimum state of the fin configuration is derived through sensitivity analysis by evaluating the geometrical parameters of the Y-shaped fin. For the same height of the fins (10 mm), the solidification time is reduced by almost 22%, and the discharging rate is enhanced by almost 26% using Y-shaped fins compared with the straight fins. The results demonstrate that the sol

The effect of thermal treatment on optical constants of pure PMMA and with addition (15 and 35) ml of coumarin at different temperatures (100, 110 and 120) C⁰ for 1 hour were investigated. Cast method used to prepares films of pure PMMA and PMMA with (15 and 35) of coumarin. UV/VIS spectrometer technique used to measure the absorption spectra for these films. The optical constant (absorption spectra and absorption coefficient) don’t changes after applied temperatures in pure PMMA film but the optical constant (absorption spectra and absorption coefficient) in PMMA with (15 and 35) ml of coumarin increased with applied temperatures. The optical energy gap of pure PMMA and PMMA with (15 and 35) ml of coumarin sl

This study deals with free convection heat transfer for the outer surface of two
cylinders of the shape of (Triangular & Rectangular fined cylinders with 8-fins),
putted into two different spaces; small one with dimension of (Length=1.2m,
height=1m, width=0.9m) and large one with dimension of (Length=3.6m, height =3m,
width=2.7m). The experimental work was conducted with air as a heat transport
medium. These cylinders were fixed at different slope angles (0o, 30o, 60o and 90o)
.The heat fluxes were (279, 1012, 1958, 3005, 4419) W/m2, where heat transferred by
convection and radiation. In large space, the results show that the heat transfer from
the triangular finned cylinder is maximum at a slope angle equals

Background: Oral SCC is a complex malignancy where environmental factors, viral infections and genetic alterations most likely interact, and thus give rise to the malignant condition. The HSP70 play a direct role in apoptosis inhibition by aligning the improved integrity of a cell’s proteins with the improved chances of that particular cell’s survival.P21 gene produces p21 protein which is a potent cyclin-dependent kinase inhibitor that plays a significant role in carcinogenesis. The aims of the study were to evaluate and compare the immun-histochemical expression of the HSP70 and cell cycle protein p21in NOM, OED, and OSCC. Correlate both marker expressions with each other. Materials and methods: Forty six formalin-fixed, par